Key Engineering Materials Vols. 368-372

Abstract: The vapor decomposition of chelated tetrabutyl titanate on glass substrate was used for the preparation of titania films. The influences of decomposition temperature, chelant concentration on the photocatalytic properties of titania film were investigated. The films were characterized by XRD, ATR and the precursor solution was characterized by DTA.

Abstract: High quality nano-scaled fluorine and nitrogen co-doped anatase phase TiO2 can be obtained from the conversion of ammonium oxotrifluorotitanate by thermal treatment. The photocatalytic activity of TiO2 treated at 800oC shows the highest photocatalytic activity and is about 1.3 times of commercial P-25. The heterojunctions of ZnSe/TiO2 and ZnS/TiO2 prepared by metal organic vapor phase epitaxy shows 2.0 and 1.5 times the photocatalytic activities of commercial P-25. In this study, nano-scaled TiO2, ZnSe/TiO2 and ZnS/TiO2 heterojunctions show one to one correspondence between carrier lifetime and photocatalytic activity.

Abstract: Nano-TiO2 was modified with a titanate coupling agent, LICA38 [neopentyl (dially) oxy, tri (-dioctyl) pyrophosphate titanate]. X-ray photoelectron spectroscopy (XPS) was used to evaluate the surface characteristics of the bare and the modified nano-TiO2. It was demonstrated that the carbon content of the bare TiO2 is 37.9 atm. %, and that of the modified TiO2 is 47.2 atm. %. Moreover, the density of the -C-H (-C-C) and -C-O groups increases due to modification, and the atomic percentage of C=O and -OH groups reduces. These results indicate that the -C-H (-C-C) and -C-O groups from LICA38 have been introduced to the surface of nano-TiO2 by coupling reaction with the hydroxyl groups.

Abstract: Raspberry-like TiO2/Cu composite particles were prepared under mild conditions (75°C and ambient pressure) by hydrolysis of Ti(OBu)4 in acidic aqueous solution and subsequent reflux in the presence of micron size Cu powders. A 3-level and 4-factor design was employed to evaluate the effect of the main parameters on the coating quality. TiO2 particles of approximate 100nm in size were found coating on the surfaces of Cu powders to form raspberry-like structure. Ti and Cu element mainly existed on the composite particle surface as the chemical state of Ti4+ and Cu2+. TG-DTA analysis showed the TiO2 coating increased the thermal stability of Cu particles. The composite particles began oxidizing at 400°C while pure copper particles oxidized at 200°C.

Abstract: With the approach of anodic oxidation, TiO2/Ti film doped with Cu2+ was produced in H2SO4 electrolyte mixed with CuSO4. The surface morphology and the roughness of the films were studied with atomic force microscopy. The phase composition of the films was studied by X-ray diffraction. The photocatalytic activity of the films was compared through the photocatalytic degradation rate of phenol. The relations of the photocatalytic activity to the concentration of Cu2+, the microstructure and the surface roughness of the film were investigated. The results showed that Cu2+ increased the surface roughness and restrained the growth of crystal. In addition, the phenol in aqueous solution was successfully photodegraded under visible light irradiation by Cu2+-TiO2/Ti film. The composition and structure of the film affected the catalytic activity greatly. Compared with TiO2/Ti film, the recombination rate of e- and h+ of Cu2+-TiO2/Ti film was decreased.

Abstract: N-doped TiO2 nanostructured composite (TiO2-N) films with excellent photocatalytic performance under visible light were successfully formed on glass and stainless steel substrates by spin-coating process. The photoreduction performance of as-prepared coatings was characterization by reduction of Ag+ and measurement of photovoltaic response. It was found that Ag+ can be easily reduced to metallic Ag and obvious photocurrent and photovoltage were observed by V-I recording under visible light irradiation. Crystalline structure, nitrogen states in the lattice, composition and surface morphology of the nanostructured films were analyzed by XRD, XPS and SEM.

Abstract: Using TiOSO4 as precursor, Fe(NO3)3⋅9H2O as the source of Fe, CN3H5⋅HCl as the source of N, Fe/N co-doped TiO2 powder has been prepared by hydrothermal method. The as-prepared powders were characterized by XRD, BET, TEM and UV-Vis spectrophotometer. The nanocrystalline Fe/N Co-doped TiO2 powders are composed of anatase and show light-yellow in color. The grain size is about 11.1nm and the specific surface area is 145m2/g. XPS results show that N atoms and Fe atoms were incorporated into the lattice of TiO2 and the concentration of N and Fe doped in TiO2 was 0.8at% and 2.2at%, respectively. The UV-Vis diffuse reflection spectra indicate that the absorption edges of the co-doped TiO2 powders has well red-shifted into visible light region up to 606nm. The Fe/N co-doped TiO2 exhibits excellent photocatalytic activity by sterilizing E. coli completely within 1 hour under visible light irradiation.

Abstract: Photocatalytic paint was prepared by adding Fe-doped TiO2 nanocrystalline powders into self-engineered oxidation-resistant latex paint system. The UV-Vis diffuse reflectance spectroscopy was used to characterize the light absorption properties of the paint. The colony counting method was used to study photocatalytic sterilization ratio of E. coli under visible light irradiation. Effects of the kinds and amounts of TiO2 powders added in the paint on the sterilization ratio under visible light irradiation with fixed relative humidity were systematically investigated. The UV-Vis diffuse reflectance spectroscopy indicates that the absorption thresholds of the Fe-doped TiO2 paint have red-shifted into visible light region. The antibacterial experiment results show that the sterilization ratio of E. coli can exceed more than 99% in less than 4 hours under 400-lux-visible light irradiation under RH of 55%.

Abstract: Titania-silica nanocomposites with different TiO2/SiO2 compositions have been prepared by a sol-gel and hybrid method from tetraethylorthosilicate (TEOS) and tetrabutyl titanate(TBT) and β-Cyclodextrin as a pore-forming template. Drying and calcining of the hybrid xerogel can lead to the formation of nanoporous particles with surface areas in the range of 298-418 m2/g. The effect of the β-cyclodextrin concentration, the molar ratio of TiO2/SiO2 and the calcining temperature on the phase composition and structural properties of TiO2/SiO2 composites were also investigated. The results show that an increase in β-cyclodextrin concentration can lead to a decrease of the surface area and an increase of average pore size, which can be controlled by the amount of β- cyclodextrin in the hybrid sol.

Abstract: The high efficient WO3-TiO2/Ti ceramic film was prepared on the surface of titanium by the approach of anodic oxidation in order to make the absorbable spectrum of catalyst spread to the visible region and restrain the high recombination rate of electron-hole pairs during photoreaction. The surface morphology and the distribution of elements were studied with scanning electron microscopy and energy dispersive spectroscopy. The phase composition of the films was investigated with XRD. The results showed that the main components in the coating were WO3, rutile TiO2 and anatase TiO2. The compound WO3-TiO2/Ti ceramic film enlarged the range of the reacting visible light and increased the absorbing intensity. The rhodamine B was successfully photodegraded under visible light irradiation by WO3-TiO2/Ti catalyst films. It was found that the highest degradation rate of rhodamine B was achieved through an optimal W dosage of 4.2 %(wt %) in WO3-TiO2/Ti ceramic film. It was also confirmed that the recombination rate of electron-hole pairs in WO3-TiO2/Ti ceramic film declined due to the existence of WO3 in TiO2/Ti ceramic film.